Excitonic absorption in gate controlled graphene quantum dots

TL;DR

This paper develops a theoretical model for excitonic absorption in gate-controlled graphene quantum dots, predicting how their optical properties depend on shape, size, edges, and external gating, with potential applications across multiple spectral ranges.

Contribution

It introduces a comprehensive theoretical framework combining tight-binding, Hartree-Fock, and configuration interaction methods to analyze excitonic effects in large graphene quantum dots.

Findings

Triangular graphene quantum dots exhibit optical transitions in THz, visible, and UV ranges.

Optical properties are tunable via external gate controlling magnetic moment and charge density.

Strong electron-electron and excitonic interactions influence the optical spectra.

Abstract

We present a theory of excitonic processes in gate controlled graphene quantum dots. The dependence of the energy gap on shape, size and edge for graphene quantum dots with up to a million atoms is predicted. Using a combination of tight-binding, Hartree-Fock and configuration interaction methods, we show that triangular graphene quantum dots with zigzag edges exhibit optical transitions simultaneously in the THz, visible and UV spectral ranges, determined by strong electron-electron and excitonic interactions. The relationship between optical properties and finite magnetic moment and charge density controlled by an external gate is predicted.